Move the message definitions to their own files.

xfa/fwl/core/ifwl_comboboxproxy.h

Index: xfa/fwl/core/ifwl_comboboxproxy.h
diff --git a/xfa/fwl/core/ifwl_comboboxproxy.h b/xfa/fwl/core/ifwl_comboboxproxy.h
index 243937726fefa189228104eb685872e6fb52430c..7ff56232f82f3cb3dea6fa2750de773111473329 100644
--- a/xfa/fwl/core/ifwl_comboboxproxy.h
+++ b/xfa/fwl/core/ifwl_comboboxproxy.h
@@ -27,9 +27,9 @@ class IFWL_ComboBoxProxy : public IFWL_FormProxy {
   void Reset() { m_bLButtonUpSelf = false; }
 
  private:
-  void OnLButtonDown(CFWL_MsgMouse* pMsg);
-  void OnLButtonUp(CFWL_MsgMouse* pMsg);
-  void OnFocusChanged(CFWL_MsgKillFocus* pMsg, bool bSet);
+  void OnLButtonDown(CFWL_Message* pMsg);
+  void OnLButtonUp(CFWL_Message* pMsg);
+  void OnFocusChanged(CFWL_Message* pMsg, bool bSet);
 
   bool m_bLButtonDown;
   bool m_bLButtonUpSelf;